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    <script>
        //0.Number.EPSILON是JavaScript表示的最小精度
        //EPSILON属性的值接近于2.22044.。。。。自己上网查去吧
        function equal(a, b) {
            if (Math.abs(a - b) < Number.EPSILON) {
                return true;
            } else {
                return false;
            }
        }

        console.log(0.1 + 0.2 === 0.3);
        console.log(equal(0.1 + 0.2, 0.3));

        //1.二进制和八进制
        let b = 0b1010;
        let o = 0o777;
        let d = 100;
        let x = 0xff;
        console.log(b); console.log(o); console.log(d); console.log(x);

        //2.Number.isFinite 检测一个数值是否为有限数
        console.log(Number.isFinite(100));
        console.log(Number.isFinite(100 / 0));
        console.log(Number.isFinite(Infinity));


        //3.Number.isNan 检测一个数值是否为Nan
        console.log(Number.isNaN(123));



        //4.Number.parseInt Number.parseFloat 字符串转整数
        console.log(Number.parseInt('2342352655loceojj'));
        console.log(Number.parseFloat('3.1415926四杀'));

        //5.Number,isInteger 判断一个数是否为整数
        console.log(Number.isInteger(2));
        console.log(Number.isInteger(2.9));


        //6.Math.trunc 将数字的小数部分抹掉
        console.log(Math.trunc(3.77));



        //7.Math.sign 判断一个数到底为正数 负数  还是零
        console.log(Math.sign(100));
        console.log(Math.sign(0));
        console.log(Math.sign(-213));














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